i am considering starting a new thread regarding heart rate training, but i'll keep it here for now.

so i am having fun playing with my heart rate monitor doing different tasks, but it's caused me some confusion. yesterday, i did an LSD day and didn't want to go too hard b/c i was pretty sore and worn out from the past week. i noticed that when doing a rowing machine or jump rope, my heart rate was generally bouncing around 125-150. to keep it at 150, i would have to put in effort, nothing crazy, but i just had to consciously remind myself to push the pace a bit above comfort. if i didn't remind myself to go a bit faster, then i would hang around 130-135.

i also ran yesterday, and my heart rate easily ranged from 155-173. what confuses me is that it didn't take any considerable "perceived effort" to keep my heart rate at around 163. the only other time i maintained this kind of heart rate for extended periods was with hict box step ups (these were performed a week or so ago).

the only real difference between exercises that i can notice is the amount of upper body contribution. i feel that both jump rope and rowing are limited by your upper body's ability to generate power. it makes sense to me that exercises where the lower body is doing a lot of work jacks up your heart rate more. what confuses me is why the perceived effort was so different. my assumption would be that when you're HR is higher, fatigue would onset faster regardless of exercise. yet i felt that i could have maintained a heart rate of 170 running for a relatively extended period, while hitting that 170 jumping rope would have required A LOT of double unders which i could only maintain for a short period, followed by some sort of rest.

i figured the rowing machine may be tricky to analyze since you're sitting, but the jump rope threw me off.

if it is true that you can keep your HR higher for longer periods with running or other predominately lower body exercises, then how would this affect programming? is the only real purpose of including upper body motions in conditioning just to build local muscle mitochondria changes, or is there some special or equal benefit to cardiac output that cannot be generated from a lower body limiting exercise alone?

For me, the perceived difficulty would be about the added resistance. Rowing and jump roping have added weight. Try running with ankle weights (don't really do this) and you'd probably have the same effect.